The problem with many Christians is that while they have made a decision to become a Christian by trusting in Jesus Christ for their salvation, they have not yet made a decision to become a disciple. They have not surrendered their lives in such a way so as to be a committed follower of Jesus Christ. The difference between a decision-maker and a follower is simply surrender.
What Paul is telling us in the passage of Romans 12:1,2 is that God wants us to present us to Him. He wants you to put you on the altar. You are to present your life – that means all of you – to Him on His altar. Keep in mind, in the Old Testament times when a sacrifice was placed on an altar, the Priest did not just put the head, or the arm, or a portion of the lamb on the altar. He put the entirety of the being on the altar. What too many believers have done is put a portion of their time, talents and treasures on God’s altar and assumed it is enough.
It is not. God wants all of you to be given to Him.
In fact, throughout Scripture we read that anytime God wanted to do something big for His people, He always required a sacrifice first. There had to be something present that demonstrated sincerity and commitment. See, worship is not simply singing songs on a Sunday. True worship, as outlined in Romans 12, is giving yourself to God in your entirety. True worship includes surrender.